The present invention relates to the field of mining shovels. Specifically, the present invention relates to a rope shovel having an actively controlled bucket.
On a conventional rope shovel, a dipper is attached to a handle, and the dipper is supported by a cable, or rope, that passes over a boom sheave. The rope is secured to a bail that is pivotably coupled to the dipper. During the hoist phase, the rope is reeled in by a hoist drum, lifting the dipper upward through the bank and liberating the material to be dug. The dipper is hollow with a substantially rectangular cross-section, and the interior walls of the dipper are generally straight.
The use of the rope to hoist the dipper maximizes the lifting force during the dig cycle. However, the orientation of the dipper relative to the handle is generally fixed during a dig cycle. The operator cannot control the motion of the dipper or other attachment independent of the handle and hoist rope, limiting the ability to adjust the shovel's performance in response to variation in the digging conditions. The penetration or breakout force of the dipper is largely dependent on the hoist force and the orientation of the dipper. For example, while the hoist force is substantially vertical, the dipper is substantially horizontal with respect to the material to be dug. This significantly limits the amount of hoist force that can be transmitted to breakout force at the digging edge of the dipper. In addition, the dipper lacks versatility: in order to perform a digging operation, the dipper must typically be positioned at the base of the bank and pulled through to the top. This makes it difficult to perform selective digging, or inserting the dipper at an intermediate height of the bank and digging from that point.